Haptic feedback using composite piezoelectric actuator

ABSTRACT

An input/output device includes a touch sensitive layer configured to sense if an object touches the touch sensitive layer and to sense where the touch sensitive layer is contacted, a first electrode layer and second electrode layer, at least a portion of one of the first electrode layer and second electrode layer connected to at least a portion of the touch sensitive layer, and a composite piezoelectric layer connected between the first electrode layer and second electrode layer. The composite piezoelectric layer has a plurality of piezoelectric rods arranged in a polymer matrix. The polymer matrix provides the composite piezoelectric layer with a predetermined property. A drive circuit is configured to apply an alternating voltage to the first electrode layer and second electrode layer in response to the sensed object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/542,795, filed Aug. 18, 2009 and incorporatedherein by reference in its entirety.

FIELD

The embodiments of the present disclosure generally relate to providinghaptic feedback in a human-computer interface and more particularlyrelate to haptic feedback structures using composite piezoelectricactuators.

BACKGROUND

Electronic device manufacturers strive to produce a rich interface forusers. Conventional electronic devices often provide visual and/orauditory feedback to communicate information to users. In some cases,kinesthetic feedback (such as active and resistive force feedback)and/or tactile feedback (such as vibration, texture, and heat) may alsobe provided to the user to enhance the user experience. Generallyspeaking, kinesthetic feedback and tactile feedback are collectivelyknown as “haptic feedback” or “haptic effects.” Haptic feedback may beuseful for providing cues to alert the user of specific events or toprovide realistic feedback sensations to create a greater sensoryexperience. Haptic feedback can be used with common electronic devicesand even devices used for creating a simulated or virtual environment.

In order to generate haptic effects, some type of haptic actuator can beutilized. Examples of known haptic actuators include electromagneticactuators, such as an Eccentric Rotating Mass (“ERM”) in which aneccentric mass is moved by a motor, a Linear Resonant Actuator (“LRA”)in which a mass attached to a spring is driven back and forth, a “smartmaterial” such as piezoelectric material, electro-active polymers, orshape memory alloys, etc. Many of these actuators and the devices withwhich they interact typically have resonant frequencies, which can bebuilt in or dynamically determined. Drive signals can be applied to theactuators to generate the haptic effects effectively and efficiently.

SUMMARY

The present disclosure describes embodiments of systems, electronicdevices, and input/output devices for providing haptic feedback to auser. In some embodiments, a human-computer interface includes a displaydevice and a touch sensitive device. The display device is configured tovisually display images to a user and the touch sensitive device isconfigured to sense contact with the user. Furthermore, thehuman-computer interface includes a composite piezoelectric layerpositioned between the display device and the touch sensitive device.The composite piezoelectric layer is configured to provide hapticfeedback to the user.

The embodiments described in the present disclosure may include variousfeatures and advantages, which may not necessarily be expresslydisclosed herein but will be apparent to one of ordinary skill in theart upon examination of the following detailed description andaccompanying drawings. It is intended that these features and advantagesbe included within the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The components of the following figures are illustrated to emphasize thegeneral principles of the present disclosure and are not necessarilydrawn to scale. Reference characters designating correspondingcomponents are repeated as necessary throughout the figures for the sakeof consistency and clarity.

FIG. 1 is a block diagram showing a general schematic of an electronicdevice, according to various embodiments of the invention.

FIG. 2A is a diagram illustrating an exploded view of a human-computerinterface, according to various embodiments of the invention.

FIG. 2B is a diagram illustrating an assembled view of thehuman-computer interface of FIG. 2A, according to various embodiments ofthe invention.

FIG. 3 is a diagram illustrating an embodiment of a touch surface deviceand illustrating a side view of a laminated structure of the touchsurface device, according to various embodiments of the invention.

FIG. 4 is a diagram illustrating a perspective view of a section of acomposite piezoelectric structure, according to various embodiments ofthe invention.

DETAILED DESCRIPTION

The present disclosure describes embodiments of haptic feedbackactuators that impose haptic effects on a user via a user interface,human-computer interface, or other portions of a user device on which orwithin which the actuators reside. In particular, the embodiments of thehaptic feedback actuators described herein can be configured to applyhaptic effects to a touch sensitive surface of a user device. The touchsensitive surface, in some embodiments, can be part of a display devicethat may include both a visual output mechanism and a touch sensitiveinput mechanism. Thus, haptic feedback can be applied in user devices,such as electronic handheld devices, for providing a rich sensoryexperience for the user.

Various haptic actuation technologies have been used in the past toprovide vibrotactile haptic feedback to touch sensitive devices, such astouch screens. Known haptic feedback devices use electric actuators,such as Linear Resonant Actuator (“LRA”) devices and Eccentric RotatingMass (“ERM”) devices. However, these actuators are generally notscalable and do not always performance sufficiently in hapticapplications. These devices are often very bulky and can have difficultymeeting certain space limitations. Furthermore, these types of devicesusually consume a large amount of power.

Another conventional haptic feedback technology in touch sensitivedevices is electro-active polymer (“EAP”) devices. One drawback of thistechnology, however, is that EAP-based actuators normally requirethousands of volts of electricity to provide effects that are suitablefor haptic applications.

Development of haptic feedback structures has led to smaller, morecompact devices. Hence, another line of technologies for providinghaptic feedback in touch sensitive devices is monolithic piezoelectricceramics. Actuators made from these ceramics, referred to as monolithicpiezoelectric actuators, offer satisfactory solutions for hapticfeedback because of their scalability and fast dynamics. However, themechanical integration and mounting of such actuators into consumerproducts can often be troublesome. Also, monolithic piezoelectricceramics are normally quite fragile and brittle and can break if theelectronic device incorporating the ceramics is dropped or if itexperiences other similar forces or stresses. It can be difficult attimes to integrate monolithic piezoelectric ceramics into commercializedproducts.

In contrast with the use of monolithic piezoelectric actuators, thepresent disclosure describes use of “composite piezoelectric actuators”to provide haptic feedback. Composite piezoelectric material may be usedto achieve specific characteristics of a haptic feedback device. Forinstance, mechanical strength, stiffness, damping coefficients,toughness, flexibility, displacement to length ratio, power consumption,actuation force, etc., can be optimized to meet particularelectromechanical targets for specific applications. In addition,because of the flexibility characteristics of composite piezoelectricmaterial, the haptic feedback actuators can serve as a viscoelasticsuspension for a touch screen, which can be placed on a haptic feedbackactuator. By tuning the viscoelastic characteristics, the resonantfrequency of the touch screen structure can be adjusted.

In some embodiments, the composite piezoelectric actuators can be formedas “haptic tape,” which may have a form factor similar to regular tape.In contrast to regular tape, however, haptic tape can be stimulated inany suitable manner to provide haptic feedback to a user touching thetape. Furthermore, when the composite piezoelectric actuators arecreated in haptic tape form, the tape can also serve as a sealantbetween two components. For example, in the case of using haptic tapewith a touch screen, the haptic tape acts as a sealant between a touchsurface layer and an underlying display device, such as a liquid crystaldisplay (“LCD”).

Although many of the examples described herein relate to touch screendevices, it should be understood that the present disclosure alsoencompasses other types of human-computer interfaces involving touchsensitive structures. In addition, other features and advantages will beapparent to one of ordinary skill in the art upon reading andunderstanding the general principles of the present disclosure. Theseother features and advantages are intended to be included in the presentdisclosure as well.

FIG. 1 is a block diagram of an electronic device 10 in accordance withone embodiment. More particularly, electronic device 10 includes aprocessing device 12, a memory device 14, and input/output devices 16,which are interconnected via a bus 18. Furthermore, input/output devices16 includes a touch screen device 20 or other human-computer interfacedevices.

Touch screen device 20 may be configured as any suitable human-computerinterface or touch/contact surface assembly. Touch screen device 20 maybe any touch screen, touch pad, touch sensitive structure, computermonitor, laptop display device, workbook display device, kiosk screen,portable electronic device screen, or other suitable touch sensitivedevice. Touch screen device 20 may be configured for physicalinteraction with a user-controlled device, such as a stylus, finger,etc. In some embodiments, touch screen device 20 may include at leastone output device and at least one input device. For example, touchscreen device 20 might include a visual display and a touch sensitivescreen superimposed thereon to receive inputs from a user's finger.

In various embodiments, touch screen device 20 provides haptic feedbackto at least a portion of electronic device 10, which can be conveyed toa user in contact with electronic device 10. Particularly, touch screendevice 20 can provide haptic feedback to the touch screen itself toimpose a haptic effect when the user in is contact with the screen. Thehaptic effects can be used to enhance the user experience, andparticularly can provide a confirmation to the user that the user hasmade sufficient contact with the screen to be detected by touch screendevice 20.

Electronic device 10 may be any device, such as a desk top computer,laptop computer, electronic workbook, electronic handheld device (suchas a mobile phone, gaming device, personal digital assistant (“PDA”),portable e-mail device, portable Internet access device, calculator,etc.), kiosk (such as an automated teller machine, ticking purchasingmachine, etc.), printer, point-of-sale device, game controller, or otherelectronic device.

Processing device 12 may be a general-purpose or specific-purposeprocessor or microcontroller for managing or controlling the operationsand functions of electronic device 10. For example, processing device 12may be specifically designed as an application-specific integratedcircuit (“ASIC”) to control output signals to a driver of input/outputdevices 16 to provide haptic effects. Processing device 12 may beconfigured to decide, based on predefined factors, what haptic effectsare to be played, the order in which the haptic effects are played, andthe magnitude, frequency, duration, and/or other parameters of thehaptic effects. Processing device 12 can also be configured to providestreaming motor commands that can be used to drive the haptic actuatorsfor providing a particular haptic effect. In some embodiments,processing device 12 may actually include a plurality of processors,each configured to perform certain functions within electronic device10.

Memory device 14 may include one or more internally fixed storage units,removable storage units, and/or remotely accessible storage units. Thevarious storage units may include any combination of volatile memory andnon-volatile memory. The storage units may be configured to store anycombination of information, data, instructions, software code, etc. Moreparticularly, the storage devices may include haptic effect profiles,instructions for how the haptic actuation devices of input/outputdevices 16 are to be driven, or other information for generating hapticeffects.

In addition to touch screen device 20, input/output devices 16 may alsoinclude specific input mechanisms and output mechanisms. For example,the input mechanisms may include such devices as keyboards, keypads,cursor control devices (e.g., computer mice), or other data entrydevices. Output mechanisms may include a computer monitor, virtualreality display device, audio output device, printer, or otherperipheral devices. Input/output devices 16 may include mechanisms thatare designed to not only receive input from a user and but also providefeedback to the user, such as many examples of touch screen devices.Touch screen device 20 and other input/out devices 16 may include anysuitable combination and configuration of buttons, keypads, cursorcontrol devices, touch screen components, stylus-receptive components,or other data entry components. Touch screen device 20 may also includeany suitable combination of computer monitors, display screens, touchscreen displays, haptic or tactile actuators, haptic effect devices, orother notification devices for providing output to the user.

FIG. 2A is a diagram illustrating an exploded view of an embodiment of ahuman-computer interface 22. FIG. 2B is a diagram illustrating anassembled view of the embodiment of human-computer interface 22 of FIG.2A. Human-computer interface 22 in this embodiment includes a display24, a composite piezoelectric assembly 26, and a touch sensitive device28. In some embodiments, display 24 is an LCD. In addition to thefunctionality of sensing touch, touch sensitive device 28 may alsoinclude a protective layer for protecting the other layers fromenvironmental effects. Although the components of human-computerinterface 22 are shown as planar layers, it should be noted thatcomposite piezoelectric assembly 26 and touch sensitive device 28 can beconfigured as flexible layers and are capable of conforming to any shapeof display 24.

In some embodiments, composite piezoelectric assembly 26 can have a formfactor similar to adhesive tape. Also, composite piezoelectric assembly26 may have an adhesive material applied to one or both sides of thetape, allowing composite piezoelectric assembly 26 to adhere to thesurfaces of adjacent objects, such as display 24 and touch sensitivedevice 28 in this example. The adhesive material may allow compositepiezoelectric assembly 26 to be bonded to the surface of another objectwithout the need for screws or other securing mechanisms. Moreparticularly, when configured as adhesive tape, composite piezoelectricassembly 26 is a haptic tape that is capable of providing hapticfeedback to a user. Therefore, although composite piezoelectric assembly26 can be very thin, it is still able to provide haptic effects that canbe sensed by a user.

Composite piezoelectric assembly 26 may include at least two electrodelayers placed on opposite sides of a composite piezoelectric layer.Composite piezoelectric layers are manufactured and supplied, forexample, by Smart Material Corporation based in Sarasota, Fla. When avoltage is applied to the opposing electrode layers to stimulate thecomposite piezoelectric layer, the composite piezoelectric layerresponds by deforming its shape in a direction perpendicular to theplane of the layer. More particularly, the composite piezoelectric layerexpands and contracts, whereby the layer primarily changes with respectto its thickness and its length and width remain substantially the same.As a result, when display 24 is maintained in a substantially fixedposition, composite piezoelectric assembly 26 can be stimulated to movetouch sensitive device 28 in an in-and-out motion.

Furthermore, composite piezoelectric assembly 26 can be formed as isshown in FIG. 2A, like a frame around the outside of display 24.Particularly, composite piezoelectric assembly 26 can be formed fromfour narrows lengths of material to create a rectangle or can include arectangular planar portion having a rectangular cut-out in its center.In this configuration, composite piezoelectric assembly 26 forms a sealwith touch sensitive device 28 to protect display 24 from theenvironment. Composite piezoelectric assembly 26 can be formed tocompletely surround the perimeter of display device 24. In otherembodiments, however, it can be configured to only partially surroundthe perimeter.

In some embodiments, composite piezoelectric assembly 26 may be placedon the other side of display 24 away from touch sensitive device 28 toprovide haptic feedback to the entire display device. Compositepiezoelectric assembly 26 can be uniform throughout its structurewithout a cutout in the middle thereof. This structure may help toprovide an equal distribution of haptic effects to all portions ofdisplay 24. Also, with composite piezoelectric assembly 26 behinddisplay 24, composite piezoelectric assembly does not block any portionof the user's view of display 24. Furthermore, composite piezoelectricassembly 26 may not need to act as a sealant as described above sincetouch sensitive device 28 can be used to protect display 24. Therefore,composite piezoelectric assembly 26 can be formed with any desired formfactor with no particular concern for the functionality of providingsealing properties.

FIG. 3 is a diagram illustrating an embodiment of a touch surface device30. In some embodiments, the structure of touch surface device 30 mayinclude similar components and functionality as the human-computerinterface 22 described with respect to FIGS. 2A and 2B. As illustratedin FIG. 3, touch surface device 30 includes an actuator drive circuit 32shown in block form and an embodiment of a laminated structure 34 shownfrom a cross-sectional side view. Laminated structure 34 in thisembodiment includes a touch sensitive layer 36, a first electrode layer38, a composite piezoelectric layer 40, a second electrode layer 42, anda display layer 44 (e.g., an LCD layer). In some embodiments, layers 38,40, and 42 can make up a composite piezoelectric assembly, such ascomposite piezoelectric assembly 26 shown in FIG. 2. In someembodiments, laminated structure 34 may include an additional protectivelayer positioned on top of touch sensitive layer 36 to protect theunderlying layers from the environment and from the user's touch. Thethickness of each layer is not necessarily drawn to scale and does notnecessarily represent the relative dimensions of the layer with respectto the other layers. Other layers and/or other layer configurations mayalso be used.

Electrode layers 38 and 42 can be designed to have substantially thesame flexibility as composite piezoelectric layer 40 and/or touchsensitive layer 36 in order to allow layered structure 34 to properlyconform to the shape of the surface of display layer 44. Electrodelayers 38 and 42 may be formed on opposite sides of compositepiezoelectric layer 40 and may be connected to actuator drive circuit32, which may be controlled by processing device 12 (FIG. 1) or anotherprocessor. Actuator drive circuit 32 is configured to stimulatecomposite piezoelectric layer 40 to cause it to expand or contract,thereby generating a haptic effect that can be sensed by the user. Theelectrode layers 38 and 42 are electrically conductive layers forallowing the signals from actuator drive circuit 32 to be distributedacross composite piezoelectric layer 40. In some embodiments, electrodelayers 38 and 42 equally distribute the signals across compositepiezoelectric layer 40. Also, layered structure 34 may be designed suchthat electrode layers 38 and 42 are electrically in communication withpiezoelectric rods or other piezoelectric structure running widthwisethrough composite piezoelectric layer 40.

FIG. 4 is a diagram illustrating a section of an embodiment of acomposite piezoelectric structure 46. In this embodiment, compositepiezoelectric structure 46 includes an array of piezoelectric rods 48embedded in a polymer matrix 50. With this arrangement, the stimulationof piezoelectric rods 48 causes the rods to expand or contractlongitudinally.

Generally, composite piezoelectric material contains piezoelectricceramic fibers, such as piezoelectric rods 48, embedded in a certainpattern within a matrix of polymer. With such an arrangement, it can bepossible to achieve desired mechanical and electrical characteristicsfor specific haptic effects. One realization of this arrangement is a“1-3 composite piezo” arrangement, which is the arrangement shown inFIG. 4. Specifically, the piezoelectric fibers or rods are arranged inone-dimension along a y-axis within a three-dimensional xyz polymermatrix. Properties that normally cannot be achieved by each of thecomponents alone can be achieved by attaching these materials at a microlevel or macro level within the context of various connectivitypatterns.

Various arrangements of piezoelectric rods 48 and polymer matrix 50 mayprovide advantages when used as a haptic feedback actuator. For example,some arrangements may be quite robust and may operate sufficientlywithin a handheld device subject to various forces or stresses, such asthe force of being dropped on a hard surface. Also, some arrangementsallow the structure to be flexible, allowing the structure to be appliedto practically any shaped surface. Some arrangements can be very thin,even to a thickness similar to the form factor of adhesive tape.Therefore, it can be operative even with a very small size.

In embodiments where the composite piezoelectric structure is formed ashaptic tape, it can also be used as a sealant. Haptic tape is alsoscalable to any desired dimensions. Also, it can be secured using anysuitable adhesive, which can be easier than other securing componentssuch as screws. Furthermore, composite piezoelectric structure 46 can beoperated efficiently while consuming a small amount of power.

Composite piezoelectric structure 46 can be integrated as an actuatorbetween a display, such as an LCD, and a touch sensitive layer of anelectronic device. When voltage is applied to their ends, piezoelectricrods 48 deform along their longitudinal axis, thereby moving the touchsensitive layer in a direction normal to its plane or tangent. Thus,rods 48 deform up and down to cause vibration of the whole polymermatrix 50. Various haptic effects in a direction perpendicular to aplane or tangent of the surface of composite piezoelectric structure 46can be provided in this way by stimulating composite piezoelectricstructure 46 with different input voltage profiles. In some embodiments,composite piezoelectric structure 46 can be configured such that thedirection of deformation of rods 48 is lateral to thus create a lateralmotion of the touch surface.

Moreover, the viscoelastic characteristics of the polymer matrix 50 canbe tuned in a way that the structure can serve as a suspension mechanismwith a desired natural dampening frequency. The viscoelasticcharacteristics may also serve to isolate any vibration that istransferred to the touch sensitive layer from the rest of the electronicdevice, resulting in well-controlled haptic effects. Polymer matrix 50may be specifically designed to provide certain stiffness properties,dampening properties, suspension properties, softness properties,vibration properties, or other haptic related properties.

The embodiments described herein represent a number of possibleimplementations and examples and are not intended to necessarily limitthe present disclosure to any specific embodiments. Instead, variousmodifications can be made to these embodiments as would be understood byone of ordinary skill in the art. Any such modifications are intended tobe included within the spirit and scope of the present disclosure andprotected by the following claims.

What is claimed is:
 1. An input/output device comprising: a touchsensitive layer configured to sense if an object touches the touchsensitive layer and to sense where the touch sensitive layer iscontacted; a first electrode layer and second electrode layer, at leasta portion of one of the first electrode layer and second electrode layerconnected to at least a portion of the touch sensitive layer; acomposite piezoelectric layer connected between the first electrodelayer and second electrode layer, the composite piezoelectric layerhaving a plurality of piezoelectric rods arranged in a polymer matrix,the polymer matrix configured to be tuned to provide the compositepiezoelectric layer with a predetermined property; a drive circuitconfigured to apply an alternating voltage to the first electrode layerand second electrode layer in response to the sensed object.
 2. Theinput/output device according to claim 1, wherein the predeterminedproperty is a haptic related property selected from the group consistingof: stiffness, dampening, suspension, softness, and vibration.
 3. Theinput/output device according to claim 1, further comprising a displaylayer configured to visually display images.
 4. The input/output deviceaccording to claim 1, further comprising a virtual reality displaydevice.
 5. The input/output device according to claim 1, wherein thepiezoelectric rods span across the width of the composite piezoelectriclayer such that each piezoelectric rod is in contact with the firstelectrode layer and the second electrode layer.
 6. The input/outputdevice according to claim 1, wherein when the piezoelectric rods arestimulated by the alternating voltage, the piezoelectric rods expand andcontract in a longitudinal direction.
 7. The input/output deviceaccording to claim 6, wherein the expanding and contracting of thepiezoelectric rods causes the touch sensitive layer to move in adirection perpendicular to a surface or tangent of the display layer. 8.The input/output device according to claim 6, wherein the expanding andcontracting of the piezoelectric rods causes vibration of the polymermatrix in which the piezoelectric rods are arranged.
 9. An input/outputdevice comprising: a touch sensitive layer configured to sense if anobject touches the touch sensitive layer and to sense where the touchsensitive layer is contacted; a display layer configured to displayimages; a first electrode layer and a second electrode layer, at least aportion of one of the first electrode layer and the second electrodelayer connected to at least a portion of the touch sensitive layer; ahaptic tape comprising a composite piezoelectric layer connected betweenthe first electrode layer and the second electrode layer, the compositepiezoelectric layer having a plurality of piezoelectric rods arranged ina polymer matrix, the haptic tape being attached to the touch sensitivelayer and the display layer to provide a seal between the touchsensitive layer and the display layer; and a drive circuit configured toapply an alternating voltage to the first electrode layer and the secondelectrode layer in response to the sensed object to generate a hapticeffect.
 10. The input/output device according to claim 9, wherein thedisplay layer comprises a virtual reality display device.
 11. Theinput/output device according to claim 9, wherein the piezoelectric rodsspan across the width of the composite piezoelectric layer such thateach piezoelectric rod is in contact with the first electrode layer andthe second electrode layer.
 12. The input/output device according toclaim 9, wherein when the piezoelectric rods are stimulated by thealternating voltage, the piezoelectric rods expand and contract in alongitudinal direction.
 13. The input/output device according to claim12, wherein the expanding and contracting of the piezoelectric rodscauses the touch sensitive layer to move in a direction perpendicular toa surface or tangent of the display layer.
 14. The input/output deviceaccording to claim 12, wherein the expanding and contracting of thepiezoelectric rods causes vibration of the polymer matrix in which thepiezoelectric rods are arranged.
 15. A haptic tape comprising acomposite piezoelectric layer connected between a first electrode layerand a second electrode layer, the composite piezoelectric layer having aplurality of piezoelectric rods arranged in a polymer matrix, the haptictape being configured to be used as a sealant.
 16. The haptic tapeaccording to claim 15, wherein the piezoelectric rods span across thewidth of the composite piezoelectric layer such that each piezoelectricrod is in contact with the first electrode layer and the secondelectrode layer.
 17. The haptic tape according to claim 15, wherein whenthe piezoelectric rods are stimulated by an alternating voltage appliedto the first electrode layer and the second electrode layer, thepiezoelectric rods expand and contract in a longitudinal direction. 18.The haptic tape according to claim 17, wherein the expanding andcontracting of the piezoelectric rods causes vibration of the polymermatrix in which the piezoelectric rods are arranged.